package Task18;

import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
       //通过列举兔子每个月的生产情况，可以得出规律是斐波那契数列
        while (scanner.hasNext()){
            int month = 1;
            int month2 = 1;
            int month3 = 1;
            int m = scanner.nextInt();
            for (int i = 2; i < m; i++) {
                month3 = month + month2;
                month = month2;
                month2 = month3;
            }
            System.out.println(month3);
        }

    }
}
